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Full text of "The Cambridge Natural History"

388

OSTEOLOGY AND

with numerous tubercles. The carnassial tooth is often, but
by no means always, very much larger and especially longer
than the rest of the molar and premolar series. It is less
pronounced in some of the omnivorous Arctoidea. The skull of
the Carnivora is longer in the more primitive types, such as the
Canidae,, and shorter in the more specialised Felidae. The orbit
is hardly ever completely shut off by bone, though the postorbital
process of the frontal sometimes approaches the corresponding
upward process of the zygomatic arch. The palate, which is
completely ossified, sometimes reaches back for some distance
behind the teeth; it always extends as far as the last molar.
The tympanic bulla is often very inflated, and if flatter, as in the
Bears, is at any rate large and conspicuous. The lower jaw has

FIG. 191.—A, Atlas of Bog. Ventral view. x ^. B, Axis of Bog. Side view. xf.
o, Odontoid process ; ju#, posterior zygapophysis ; s, spinous process ; sn, foramen,
for first spinal nerve j t, transverse process; i?, vertebrarterial canal. (From
Flower's Osteology.)
a high eoronoid process, and the condyle is transversely elongated,
this part of the bone being rolled into an almost cylindrical
form; it fits very closely into the glenoid cavity, and the
articulation is thereby very strict—an obvious advantage in a
creature with, so great a need for powei of jaw.
In the vertebral column the atlas always has large wing-like
processes; the spine of the axis vertebra has a long antero-
posteriorly elongated form. The transverse processed of the
fourth to the sixth cervicals are, as a rule, double. These
features, however, though characteristic of the Carnivora are not
by any means distinctive. The true sacrum consists of hut a
single vertebra to which the ilia are attached; but at most two
other vertebrae are fused with this. The clavicle is always small
anil sometimes quite rudimentary, or even absent. The spine of
tfcfe scapiala is weH developed, and almost equally divides th«